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authorJack Sangdahl <[email protected]>2024-11-24 21:10:51 -0700
committerJack Sangdahl <[email protected]>2024-11-24 21:10:51 -0700
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773. sliding puzzle
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+# 773. Sliding Puzzle
+from collections import deque
+
+"""
+on an empty 2 x 3 board there are five tiles labeled from 1 to 5 and an empty
+square represented by 0. a move consists of choosing 0 and a 4-directionall
+adjacent number and swapping it. the state of the board is solved if and only
+if the board is '[[1,2,3],[4,5,0]]'. given the puzzle 'board', return the
+least number of moves required so that the state of the board is solved. if
+it is impossible for the state of the board to be solved, return -1
+"""
+
+
+class Solution(object):
+ def slidingPuzzle(self, board):
+ """
+ :type board: List[List[int]]
+ :rtype: int
+ """
+ s = "".join(str(n) for r in board for n in r)
+ dq, vis = deque(), {s}
+ dq.append((s, s.index("0")))
+ steps, height, width = 0, len(board), len(board[0])
+ while dq:
+ for _ in range(len(dq)):
+ t, i = dq.popleft()
+ if t == "123450":
+ return steps
+ x, y = i // width, i % width
+ for r, c in (x, y + 1), (x, y - 1), (x + 1, y), (x - 1, y):
+ if height > r >= 0 <= c < width:
+ ch = [n for n in t]
+ ch[i], ch[r * width + c] = ch[r * width + c], "0"
+ s = "".join(ch)
+ if s not in vis:
+ vis.add(s)
+ dq.append((s, r * width + c))
+ steps += 1
+ return -1
+
+
+if __name__ == "__main__":
+ obj = Solution()
+ print(obj.slidingPuzzle(board=[[1, 2, 3], [4, 0, 5]]))
+ print(obj.slidingPuzzle(board=[[1, 2, 3], [5, 4, 0]]))
+ print(obj.slidingPuzzle(board=[[4, 1, 2], [5, 0, 3]]))